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MSD Exhibit No. MSD 3L
2023 Wastewater Rate Change Proceeding
WILLIAM ZIEBURTZ
Direct Testimony
Metropolitan St. Louis Sewer District
March 24, 2023
Table of Contents
Page
Witness Background and Experience ........................................................................................... 1
I/I Cost Allocation Study and Recommendation .......................................................................... 1
Direct Testimony of William Zieburtz, Stantec Consulting Services Inc. March 24, 2023
2023 Wastewater Rate Proceeding 1 MSD Exhibit No. MSD 3L
Witness Background and Experience 1
Q1. Please state your name, business address, and telephone number. 2
A. William B. Zieburtz, Jr., 220 Peachtree Street NE, Suite 1900, Atlanta, GA 30303, 770-3
853-0025. 4
Q2. What is your occupation? 5
A. Utility Rate Consultant for Stantec Consulting Services Inc. 6
Q3. How long have you been associated with Stantec? 7
A. 8 years. 8
Q4. What is your professional experience? 9
A. I have provided economic and financial consulting services to the water and wastewater 10
industry since 1986. My focus has been on utility cost of service, rate, financial planning, 11
and rate design services. 12
Q5. What is your educational background? 13
A. I earned a BBA from the University of Georgia with a major in economics in 1982 and an 14
MA in 1985, also in economics. 15
I/I Cost Allocation Study and Recommendation 16
Q6. Please describe your role in this proceeding? 17
A. The Metropolitan St. Louis Sewer District (District or MSD) requested that Stantec 18
examine MSD’s allocation and recovery of costs related to infiltration and inflow (I/I) 19
between customer and volumetric charges in response to a Rate Commission 20
recommendation. Our report was delivered to MSD on October 10, 2022. I served as 21
Director for that project. 22
Q7. What is infiltration and inflow? 23
A. “Infiltration and inflow” is a phrase referring to the entry of extraneous flows into a 24
Direct Testimony of William Zieburtz, Stantec Consulting Services Inc. March 24, 2023
2023 Wastewater Rate Proceeding 2 MSD Exhibit No. MSD 3L
collection system. Infiltration is the name for flows from groundwater sources while 1
inflow is a reference to water entering sewers as a result of storm events. Infiltration and 2
inflow occur in all sewer systems, entering through a variety of potential entry points 3
including manholes, pipe appurtenances, private laterals, and pipe defects. Infiltration and 4
inflow consume system capacity and must be managed and treated, resulting in costs to the 5
system. This is a common occurrence in all sewer systems. 6
Q8. Is the manner in which MSD’s rate structure recovers costs associated with 7
infiltration and inflow consistent with the methodology used by other wastewater 8
utilities? 9
A. Yes. Wastewater system managers rely on a variety of approaches to address the allocation 10
of infiltration and inflow costs. While there are a variety of approaches and outcomes 11
reflecting differences in system needs, policy objectives, and engineering judgments, 12
wastewater systems often rely on an allocation of infiltration and inflow costs that reflects 13
both the number of customer connections by class and contributed wastewater volumes by 14
class. 15
Q9. What did your study entail? 16
A. Stantec acquired and analyzed data on I/I volumes in MSD’s wastewater system and on 17
MSD’s current approach to allocate I/I costs in the development of user charges. Stantec 18
developed ten different allocation approaches to recognize conditions faced by MSD. The 19
results of these I/I cost allocation approaches were evaluated and compared with the I/I 20
cost allocation processes of thirteen large wastewater utilities. See Exhibit MSD 66. 21
Q10. MSD’s most recent Wastewater Rate Change Proceeding in 2019 and historical 22
proposals since 2007 have included an allocation of 40% of I/I costs based on customer 23
connections and 60% based on contributed wastewater volume. Do you recommend 24
Direct Testimony of William Zieburtz, Stantec Consulting Services Inc. March 24, 2023
2023 Wastewater Rate Proceeding 3 MSD Exhibit No. MSD 3L
any changes to this allocation percentage? 1
A. No. 2
Q11. Why not? 3
A. First, there is no approach allowing a direct measurement of infiltration and inflow into 4
MSD’s system. Second, Stantec evaluated multiple approaches for allocating infiltration 5
and inflow costs and concluded that none of the alternative approaches is able to generate 6
an allocation of inherently higher quality than MSD’s current allocation. Third, Stantec 7
concluded that many different allocation approaches, measurements, and customer class 8
allocation results are consistent with fundamental utility objectives to achieve sufficient, 9
stable, and sustainable revenue generation and equitable cost recovery. Fourth, Stantec has 10
not observed or identified a material change in MSD’s systems or in the implications of 11
infiltration and inflow volumes and characteristics since the previous rate proceedings 12
suggesting a need for any change in the allocation of I/I costs. 13
Q12. Does this conclude your prepared direct testimony in this matter? 14
A. Yes, it does. 15